I don't know if there has been a survey taken as such, but it's very obvious to those of us who attend a lot of these that there are a good number of people, big companies, etc., who, since it became a statutory holiday, have moved it to the nearest Friday or the nearest Monday, thereby taking a long weekend and disappearing to go fishing, to go shopping, or to go wherever they decide to go.
On June 6th, 2006. See this statement in context.